LONDON, Feb 7 (Reuters) - Oil prices fell to a one-month low Wednesday, after U.S. data showed an unexpected build in refined products, fanning fears of oversupply headed into the slow demand season and offsetting a bounce after the largest UK pipeline shut for the second time in three months.

The Brent crude futures contract was down 30 cents at $66.57 a barrel at 10:41 a.m. EST (1541 GMT), while U.S. West Texas Intermediate (WTI) crude futures dropped 81 cents, or 1.3 percent, to $62.58 a barrel. U.S. crude hit a low of $62.36, the lowest level since Jan. 9.

Crude inventories rose by 1.9 million barrels in the week to Feb. 2, compared with analysts' expectations for an increase of 3.2 million barrels. Refining runs notched a surprising rise in the week, boosting inventories of distillates such as diesel and jet fuel, as well as gasoline.

The rebound in refining runs was largely due to more activity in the U.S. Gulf and the Midwest, and that helped restrain crude inventories while stocks of finished products grew more than expected.

"The report was squarely bearish with the across-the-board inventory rise. The ability of crude oil inventories to rise in the face of a snap back higher in refinery utilization was particularly bearish," said John Kilduff, partner at energy hedge fund Again Capital LLC in New York.

The market had briefly recovered after Ineos, which owns the Forties Pipeline, the largest in the United Kingdom, said the line was down after a feed control valve shut, with no clear timeline for restart.

The Forties Pipeline shut for more about three weeks in December after a crack developed in the line. That line pumps 450,000 barrels of oil a day, and its role as a supply source for the UK means it can have a notable effect on oil prices.

The increased U.S. inventories and the Forties line shutdown had an immediate effect on the WTI/Brent spread WTCLc1-LCOc1, which increased by 41 cents to $4.16 a barrel,

The Organization of the Petroleum Exporting Countries and other producers, including Russia, have cut production since January 2017 to force down global inventories.

Crude inventories in the United States C-STK-T-EIA have fallen by 20 percent since hitting record highs in April 2017.

The futures curve shows prompt prices for oil are above those for future delivery, suggesting investors are counting on demand outpacing supply.

But rising U.S. oil production C-OUT-T-EIA has been looming over the market. Output has risen by 1 million barrels per day (bpd) in the last year to about 10 million bpd.

The U.S. Energy Information Administration (EIA) expects U.S. output to reach an average of 10.59 million bpd in 2018 and 11.18 million bpd by 2019, accelerating earlier estimates. That should continue to drive U.S. exports, pinching OPEC efforts to reduce supply, and puts the U.S. in line to potentially overtake Russia as the world's largest producer.

"The strong growth that is expected in U.S. production supports our more bearish outlook for the oil market," Hamza Khan, head of ING commodities strategy, said in a note.